The present invention relates to an apparatus for automatically dissolving a powdery resin product such as a vinyl chloride resin, an ABS resin or an MBS resin in a solvent to give a solution having a predetermined concentration for use in viscosity measurement.
When preparing resin powder or forwarding the powdery product from a manufacturing plant, the powdery product is in general subjected to quality inspection for confirming whether the product fulfills the requirements for various predetermined properties. The results thus obtained are sent back to the manufacturing plant for the improvement of production processes or they are used in the denoration of the quality in order to afford convenience to the destination or the consignee.
In case of, for instance, vinyl chloride resin powder, one of the items for quality inspection thereof is to determine the average degree of polymerization. The determination of the average degree of polymerization of a powdery resin product has currently been carried out, as specified in JIS-K-6721, by determining viscosities of solutions of a resin product having a series of proper concentrations to obtain the intrinsic viscosity thereof and then evaluating the average degree of polymerization on the basis of the resulting intrinsic viscosity. Examples of devices for the determination of such an intrinsic viscosity include an automatic viscosity-determining device available from Rigo Co., Ltd. under the trade name of VSM-052PC.F01.
The viscosity measurement by an automatic viscosity-determining apparatus requires the preparation of a series of solutions of a powdery resin sample each having a predetermined concentration. There has not conventionally been developed any apparatus for preparing such a solution by automatically dissolving a powdery resin sample in a solvent. The preparation of a solution of a powdery resin sample for use in the viscosity determination thereof requires not only accurate weighing of a powdery resin sample, but also accurate weighing of a solvent. In the conventional methods, however, such operations for the preparation of solutions used in the automatic viscosity-determination have been manually performed. Accordingly, the preparation of this type requires much labor and time and is inefficient. Moreover, operations for preparing such a solution slightly vary depending on the operators and this is reflected in the resulting measured values.